Tipula oleracea Linnaeus in West-Central California (Diptera: Tipulidae)

Abstract

Occurrence of certain European species of crane flies of the genus Tipula on coastal North America has been known for a hundred years or more. A. H. Swinton (1909) reported a single female of Tipula oleracea Linnaeus from Cape Race, southeasternmost Newfoundland. But C.P. Alexander (1942) supposed it was more likely the very similar Tipula paludosa Meigen, which has been subsequently recorded from Newfoundland and nearby Nova Scotia. The most likely explanation for the occurrence of either species on the eastern coast of North America is that immature forms – larvae and possibly eggs or pupae, for all occur in soil, near the surface – were transported in soil used as ballast in European commercial vessels (Fox, 1952). The soil was abandoned on shores near harbors and replaced by cargo destined for Europe. How either T. paludosa or T. oleracea reached the western coast of North America probably involved similar transportation of immatures. The species have spread into interior eastern North America, and have recently been reported from Michigan (Gelhaus, 2005), interior New York (Peck et al., 2006), Ontario (Peck and Olmstead, 2009), and Quebec (Taschereau et al., 2009). There is no mention of either T. paludosa or T. oleracea in C. P. Alexander’s publications on the crane flies of Washington (1949) or Oregon (1954). In his section on Tipulidae, in the Catalog of the Diptera of America North of Mexico(Stone et al., 1965), he listed only T. paludosa and only from Newfoundland and Nova Scotia. In his major work on the crane flies of California (1967:56), Alexander mentioned that T. paludosa had been found in British Columbia and seemed to be established there. He added ‘‘The species is of considerable economic importance and, unless the outbreak is controlled, may well be expected to spread southwards in the west, possibly to California.’’ As Alexander predicted, T. paludosa has, in the years since 1967, been reported from near the coasts of both Washington and Oregon. Occasional specimens of both T. paludosa and T. oleracea have, in the past 20 years, been sent to GWB for identification. Recognition of these European immigrants has been facilitated by reference to the well illustrated work of E. N. Savchenko (1961), based in part on earlier works by B. Mannheims (1952) in Germany, and R. L. Coe (1950) in Britain. Commencing in 2002, co-author Arnaud (PHA) has sent numerous specimens of T. oleracea, among other Tipulidae, collected in the vicinity of San Francisco, California, to GWB for identification. As far as we are aware, these comprise the first major, long-term collections of that species from California. Umble and Rao (2004) recorded 27 specimens of T. oleracea from three counties in extreme northwestern California and mentioned that PHA had found the species in the vicinity of San Francisco Bay. San Francisco is approximately 270 miles (435 km) south of the collection sites in northwestern California. Using mainly his own modification of Malaise traps but also collecting off walls near lights, etc., PHA has collected T. oleracea throughout the years 2003–2009, in six counties of central, near-coastal California. The species is clearly established in that area and has become so common that numerous individuals have been captured in each of those years. So far, however, we have not heard of any reports of damage to grasslands in the area. In all, 1036 individuals (581 males, 450 females, 5 damaged) of T. oleracea were captured during this study. Collections were made in Alameda, San Mateo, Santa Clara and Santa Cruz counties, around the southern San Francisco Bay, Monterey Co., somewhat south of these, and Marin Co. to the northwest. More than one-third of the specimens were collected by PHA at and near his home in suburban South San Fransisco, San Mateo County. The species was taken in every month of the year, at one of these sites or another. There were no peaks of abundance suggesting the number of generations per year. Most of the flies, however, were collected in April through August. Dates for trap collections are not precise because traps were not checked daily. The crane flies were initially preserved in small, glassine envelopes.